Oral Contraceptive Pills

The Contraceptive Epidemiology

Worldwide, 922 million women of reproductive age (or their partners) are contraceptive users.  Among the 1.9 billion women of reproductive age (15-49 years) living in the world, 1.1 billion have a need for family planning, that is, they are either current users of contraceptives. Of them, 842 million use modern methods of contraception and 80 million use traditional methods or, have an unmet need for family planning.  Also, 190 million women want to avoid pregnancy but, do not use any contraceptive method.  Among the women of reproductive age (15-49 years), 779 million contraceptive users are married & 143 million users are unmarried women.  In these 143 million unmarried women, the most common method has been seen to be the use of the pill at 26.1%.

Female sterilization and male condom have been seen to be the two most common methods used worldwide. Female sterilization is the most common contraceptive method used worldwide. In 2019, 23.7 per cent of women, that is 219 million women, were using contraception in the form of female sterilization. Three other methods having more than 100 million users worldwide are the male condom (189 million), IUD (159 million) and the pill (151 million). Overall, 45.2 per cent of contraceptive users rely on permanent or long-acting methods (female and male sterilization, IUD, implant), 46.1 per cent on a short-acting method (such as male condom, the pill, injectable and other modern methods) and 8.7 per cent on traditional methods (withdrawal, rhythm methods and other traditional methods).

Oral Contraceptive Pills: What You Need to Know


Approximately 25% of women aged 15-44 currently use contraception in the form of the pill as their method of choice. Oral contraceptive pills are either combined estrogen-progesterone (also called combined oral contraceptive pill- COC) or progesterone-only pill (POP). Progesterone is the hormone that prevents pregnancy, and the estrogen component controls menstrual bleeding. OCP’s can be used to address other health conditions, particularly menstrual-related disorders such as menstrual pain, irregular menstruation, fibroids, endometriosis-related pain, and menstrual-related migraines. If there are no medical reasons upfront on why you cannot take the pill, and you are not a smoker, you can take the pill until your menopause. However, the pill is not suitable for everyone.

Nearly all women can use COCs safely and effectively, including women who:

  • Have or have not had children
  • Are married or are not married
  • Are of any age, including adolescents and women over 40 years old
  • After childbirth and during breastfeeding (Progesterone Only Pill) & after 6 weeks (Combined OCPs)
  • Have just had an abortion, miscarriage, or ectopic pregnancy
  • Smoke cigarettes but under 35 years old
  • Have anemia now or had in the past
  • Have varicose veins
  • Are living with HIV, whether or not on antiretroviral therapy

Also, women can begin using COCs without a pelvic examination, without any blood tests or other routine laboratory tests, without cervical cancer screening & without a breast examination.

After giving birth, a woman can start OCP on day 21, 3 weeks post delivery provided that she is not breastfeeding the baby. In cases where the mother is breastfeeding the child, OCP can be started after 6 weeks safely. Progesterone Only Pill can be started post pregnancy during breast feeding.

Post miscarriage or abortion, OCPs can be started from 5 days post the event and it gives immediate protection from further unwanted pregnancy.


OCPs provide a multitude of benefits. OCPs help protect against or reduce the chances of:

  • Risk of unwanted pregnancy
  • Reduce risk of endometrial cancer
  • Reduce risk of ovarian cancer
  • Reduce the risk of colorectal cancer
  • Help in reducing symptomatic pelvic inflammatory disease
  • Reduce chances of ovarian cyst
  • Reduce chances of developing iron deficiency anemia
  • Reduce menstrual cramps, excessive menstrual bleeding & ovulation pain
  • Reduce excessive hair on face & body
  • Reduce symptoms of PCOS & Endometriosis.

Common Myths of OCPs

With the use of OCPs comes responsibilities and a lot of advantages. But along with it there are also a lot of misconceptions on the use and side effects or adverse effects with the use of OCPs. A few of the common misconceptions are debunked as follows:

  • They do not build up in a woman’s body. Women do not need a “rest” from taking COCs.
  • Do not make women infertile after they stop taking COCs.
  • Do not cause birth defects or multiple births.
  • Do not change women’s sexual behavior.
  • Do not collect in the stomach. Instead, the pill dissolves each day.
  • Do not disrupt an existing pregnancy.

Mechanism of Action of OCPs

OCPS usually contain Estrogen & Progesterone in combination known as Combined OCPs or they contain only Progesterone known as Progesterone Only Pills.

Progesterone is primarily responsible for preventing pregnancy. The main mechanism of action is the prevention of ovulation by inhibiting follicular development and thereby preventing ovulation. Progestogen negative feedback works at the hypothalamus to decrease the pulse frequency of the gonadotropin-releasing hormone (GnRH). This, in turn, reduces the secretion of follicle-stimulating hormone (FSH) and decreases the secretion of luteinizing hormone (LH). If the follicle isn’t developing, there is no increase in the estradiol levels. The progestogen negative feedback and lack of estrogen positive feedback on LH secretion inhibits the mid-cycle LH surge. With no follicle developed and no LH surge to release the follicle, ovulation is prevented.

Another primary mechanism of action is progesterone’s ability to inhibit sperm from penetrating through the cervix and upper genital tract by making the cervical mucous environment unsuitable towards sperm implantation.

Estrogen has some effect with inhibiting follicular development because of its negative feedback on the anterior pituitary with reduced FSH secretion. It’s just not as prominent as the progesterone’s effect but adds to the overall effect.

Oral Contraceptive Pills

Types of OCPs

OCPs are essentially of two types, Combined Oral Contraceptive Pills (COCs) & Progesterone Only Pills (POPs). COCs contains both Estrogen & Progesterone in various doses whereas POPs contain only Progesterone.

Combined Oral Contraceptive (COC)

The usual estrogen component is combined with a different generation of progestin components with varying degrees of androgenic and progestogenic potential. The combination is prescribed based on desirable effects and risk of adverse events with progestin component and dose of estrogen and progestin component.  Usually, Ethinyl estradiol is at a dose of less than 50 mcg in this combination of pills.

  • Estrogen component: Estradiol, Ethinylestradiol, or Estetrol
  • First-generation progestin: Norethindrone acetate, Ethynodiol diacetate, Lynestrenol, Norethynodrel
  • Second generation progestin: Levonorgestrel,dl-Norgestrel
  • Third generation progestin: Norgestimate, Gestodene, Desogestrel
  • Unclassified progestin: Drospirenone, Cyproterone acetate

Depending on withdrawal bleeding desired by the patient and as deemed clinically required, it can be prescribed as:

  • Cyclic formulations: The cyclic formulations have active hormone pills for 21-24 days, followed by 7-4 days of hormone-free pills.
  • Extended cycle formulations: extended cycle formulations have active hormone pills every day for three months, followed by a placebo week.
  • Continuous use formulation:  can be manipulated by using the only active pills from monthly formulations for one-year period, which will functionally stop all menstrual bleeding. The most common complication from the extended cycle is break-through bleeding. Any formulation of a combined oral contraceptive pill can be used in this manner, but typically the monophasic pills are the easiest to manipulate.

Initiation of COCs

Having menstrual cycles or switching from a non-hormonal method:

  • Start within 5 days after the start of menstruation with no need for any additional backup method.
  • If it is more than 5 days after the start of menstruation, start COCs any time if certain that there is no pregnancy along with a backup method for the first 7 days of starting pills.
  • If switching from an IUD, can start COCs immediately

Switching from a hormonal method:       

  • Immediately, if the hormonal method has been used consistently and correctly. No need to wait till the next menstrual cycle. No need for a backup method.
  • If switching from injectables, begin taking COCs when the repeat injection would have been given. No need for a backup method.

Breast feeding & less than 6 months after giving birth: Start taking COC 6 months after giving birth

Breast feeding & more than 6 months after giving birth:

  • If menstruation has not returned, start COCs immediately along with a backup method for the first 7 days of taking pills.
  • If menstruation has started, start COCs from the 5th day of menstruation

Not breast feeding: Start COCs at any time on days 21–28 after giving birth. No need for a backup method.

After miscarriage or abortion     

  • Start immediately. If starting within 7 days after first- or second-trimester miscarriage or abortion, no need for a backup method.
  • If it is more than 7 days after first- or second-trimester miscarriage or abortion, an additional backup method for the first 7 days of taking pills will be required.

After taking ECPs             

  • Start or restart COCs immediately after ECP usage. No need to wait till the next menstrual cycle.
  • A continuing user who needed ECPs due to pill-taking errors can continue where she left off with her current pack.
  • All women will need to use a backup method for the first 7 days of taking pills.

After taking ulipristal acetate (UPA) ECPs

  • Start or restart COCs on the 6th day after taking UPA-ECPs. No need to wait for menstrual cycle.
  • COCs and UPA interact. If COCs are started sooner, and thus both are present in the body, one or both may be less effective.
  • Will need to use a backup method from the time UPA-ECPs taken up until the time COCs are started i.e. for 7 days.

Progesterone only Pill (POP)

Most frequently formulations of POPs have drospirenone or norethindrone. Drospirenone suppresses ovulation and also has anti-mineralocorticoid activity. Norethindrone is commercially available as 0.35 mg tablets, and the dose is lower than the dose used in COC pills whereas Drospirenone is commercially available as 4 mg drospirenone. While norethindrone primarily acts by thickening cervical mucus to inhibit sperm penetration, suppressing ovulation, decreasing the mid-cycle LH and FSH surge, which slows the movement of the ovum through fallopian tubes, and alters endometrium thickness. Some progestin compounds have more potent antiandrogenic properties and, therefore more effective in treating polycystic ovary syndrome, hirsutism, and acne.

Initiation of POPs

Progesterone Only Pills (POPs) can be initiated in the same way as Combined Oral Contraceptives (COCs) are.

The most important and advantageous differences between the two are:

  • POPs can be initiated immediately post giving birth which is the biggest advantage of a POP over a COC.
  • POPs can be initiated post child delivery and irrespective of breast feeding status of the mother as Progesterone is not excreted through breast milk.
  • In case of POP initiation in less than ideal circumstances and also post the use of ECPs, an additional back up method needs to be used only for TWO days and not for seven days as in the case of COCs.
Side Effects / Adverse Effects

OCPs are a highly effective and simple method to achieve contraception. But the use of OCPs can cause a few side effects for the patient. In most cases, over a period of time the side effects decrease and cease. Most commonly seen side effects with OCPs are nausea, vomiting, headache, abdominal cramps, breast tenderness and break through bleeding.

To alleviate or reduce the signs & symptoms of nausea, OCPs should be taken with food & not on empty stomach. Also, the OCP should preferably be taken at the same time every day. Also, for the first few months, there can be break through or episodic bleeding which is very normal. This doesn’t reduce the efficacy of the OCP or make the patient susceptible to unwanted pregnancy.

Women with pre-existing cardiovascular conditions and those with known DVT should not take OCPs. OCP’s are contraindicated in smokers (more than 15 cigarettes per day) over age 35 due to significant risk for cardiovascular events and specifically deep vein thromboembolism.

Diabetic patients can see an increase in blood sugar levels for the first few months. This is because progestin in OCPs cause impaired glucose metabolism in the body. To counter it, anti-diabetic medication dosage might need to be increased initially.

OCPs can cause or exacerbate hypertension in some women. If hypertension persists then OCPs should be discontinued. Patients diagnosed with migraine should not be prescribes OCPs at all.

Patients on medication for epilepsy or tuberculosis should not be prescribed OCPs as the efficacy of OCPs are decreased due to these medications through enzymatic activity.

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